Catalytic conversion of hydrocarbon mixtures

ABSTRACT

Conversion of hydrocarbonaceous mixtures applicable principally where the charge stock is contaminated by asphaltenes, sulfurous and nitrogenous compounds as well as organometallic complexes.

Umted States Patent 11 1 1111 3,915,842 Gatsis Oct. 28, 1975 4] CATALYTIC CONVERSION 01? 1,948,058 2/1934 Szeszich 208/97 HYDRQCARBON MIXTURES 3,600,300 8/1971 Steenberg 208/108 3,622,497 11/1971 Gleim 1 208/108 Inventor: J Gatsls, Des Flames, 3,622,499 11/1971 Stine et al.... 208/108 1 3,645,912 2/1972 Gatsis 1 252/411 R [73] Asslgnee' g'' g z'lg' g 3,723,297 3/1973 Gatsis et a1. 208/95 [22] Filed: July 22, 1974 Primary ExaminerDelbert E. Gantz [21] APPL No; 490 148 Assistant ExaminerG. E. Schmitkons Attorney, Agent, or Firm-James R. Hoatson, Jr.; 52 US. Cl. 208/108; 208/251 11; 252/439; Thmas MBde;w11"am Page H 260/667; 260/675 [51] Int. Cl. CG 13/20; C07C 15/28; [57] ABSTRACT BOU 27/04 Conversion of h ydrocarbonaceous m1xtures apphcable Fleld of Search H p ip y where the charge stock i contaminated y [56] Refe Cit d asphaltenes, sulfurous and nitrogenous compounds as UNn-ED STATES PATENTS well as organometallic complexes. 1,894,926 1/1933 Varga 208/108 X 4 Claims, 1 Drawing Figure Hydracmc/rad Product, Volume Hydrogen Sulfide Partial Pressure, Male CATALYTIC CONVERSION OF HYDROCARBON MIXTURES The invention herein described relates primarily to a process for the conversion of asphaltene-containing hydrocarbonaceous mixtures commonly referred to as black oils for the removal of organo-metallic contaminants, nitrogenous and sulfurous compounds, and the conversion of heptane-insoluble asphaltenic material.

Petroleum crude oils, and topped or reduced crude oils, as well as other heavy hydrocarbon fractions and- /or distillates, including black oils, heavy cycle stocks, visbreaker liquid effluent, crude tower bottoms product, tar sand oils, etc., are contaminated by the inclusion of excessive quantities of various non-metallic and metallic impurities. Among the non-metallic impurities are nitrogen, sulfur and oxygen which exist as heteroatomic compounds. Both nitrogenous and sulfurous compounds are objectionable since the combustion of fuels containing these impurities results in the release of nitrogen oxides and sulfur oxides, presenting a serious problem with respect to atmospheric pollution.

In addition to the foregoing described contaminating influences, petroleum crude oils and other heavy hydrocarbonaceous material contain high molecular weight asphaltenic compounds. These are nondistillable, oil-insoluble coke precursors which may be complexed with sulfur, nitrogen, oxygen, and various metals. Although the metallic contaminants may exist within the hydrocarbonaceous material in a variety of forms, they are generally present as organo-metallic compounds of relatively high molecular weight, such as metallic porphyrins. A considerable quantity of the organo-metallic complexes are linked with asphaltenic and become concentrated in the residual fraction; other organo-metallic complexes are volatile, oilsoluble and are, therefore, present in the lighter distillate fraction, i.e., boiling below aabout 1,050F. (621C) A reduction in the concentration of the organometallic complexes is not easily achieved, and to the extent that the crude oil, reduced crude oil, or other heavy hydrocarbon charge stock derived therefrom becomes suitable for further processing. Notwithstanding that the concentration of these organometallic complexes may be relatively small in distillate oils, for example, often less than about ppm., calculated as if the complex existed as the elemental metal, subsequent processing techniques are adversely affected thereby. With respect to a process for hydrorefining or treating of hydrocarbon fractions and/or distillates, the presence of large quantities of asphaltenic material and organo-metallic compounds interferes considerably with the activity of the catalyst with respect to the destructive removal of the nitrogenous, sulfurous and oxygenated compounds, which function is normally the easiest for the catalytic composite to perform to an acceptable degree.

A wide variety of heavy hydrocarbon fractions and- /or distillates may be converted and treated, or decontaminated effectively through the utilization of the method of the present invention. Such heavy hydrocarbon fractions include full boiling range crude oils, topped or reduced crude oils, atmospheric distillates,

visbreaker bottoms product, heavy cycle stock from thermally or catalytically-cracked charge stocks, heavy vacuum gas oils, shale oil, tar sand oils, etc. A Wyoming sour crude oil, having a gravity of 23.2 API at 60F., is contaminated by the presence of 2.8% by weight of sulfur, 2,700 ppm. of total nitrogen, approximately ppm. of metallic complexes, computed as elemental metals, and contains a high boiling, insoluble asphaltenic fraction in an amount of about 8.5% by weight. A more difficult charge stock to convert into useful liquid hydrocarbons, is a crude tower bottoms product, having a gravity, degrees API at 60F., of 14.3, and contaminated by the presence of 3.0% by weight of sulfur, 3,830 ppm. of total nitrogen, ppm. of total metals and about 10.93% by weight of asphaltenes.

It must be acknowledged that published literature recognizes various types of processes designed to effect the hydrorefining and conversion of black oils. Thus, many literature references and/or publications might be found which disclose propane deasphalting followed by thermal cracking or coking of the resulting normally liquid product, desalting followed by halogen hydride treatment to coagulate the metallic-containing asphaltenes, etc. It is noteworthy that the latter processing schemes are unconcerned with catalytic processing of black oils.

Furthermore, with respect to catalytic processing, two principal approaches have been advanced: liquid phase and vapor phase. In the former, liquid-phase oil is passed (generally upwardly) in admixture with hy drogen, into a fixed or fluidized bed of catalyst particles. In the latter, vapor-phase oil is passed (generally downward) in admixture with hydrogen into a fixed bed of catalyst particles. Regardless of the flow configuration or the charge stock phase, I have unexpectedly discovered that when the catalytic particles comprise vanadium and when hydrogen sulfide is added to the reaction zone, there is a critical range of the hydrogen sulfide partial pressure which must be maintained to promote the maximum hydrogenation and hydrocracking activity of the vanadium catalyst. The critical range of the hydrogen sulfide partial pressure is from about 10 mole percent to about 25 mole percent.

A principal object of the present invention is to provide an improved process for the conversion of a hydrocarbon feedstock, particularly a black oil, utilizing a vanadium catalyst in conjunction with a critical range of hydrogen sulfide partial pressure.

Another object involves providing a process which affords a greater degree of asphaltene conversion to distillable hydrocarbons, thereby increasing the volumetric yield of more valuable hydrocarbons.

These, and other objectives and advantages are achieved through the use of a broad embodiment of the present invention which encompasses a process for the conversion of a hydrocarbon charge stock, which process comprises: admixing a hydrocarbon charge stock with a catalyst comprising vanadium and reacting the resulting mixture with hydrogen and added hydrogen sulfide at hydrocarbon conversion conditions, characterized in that the partial pressure of said hydrogen sulfide is from about 10 mole percent to about 25 mole percent.

Other embodiments of my invention reside in the use of particular operating conditions.

The inventive concept encompassed by the foregoing described embodiments stem from the recognition of the criticality of the hydrogen sulfide partial pressure in the hydrocarbon reaction zone.

Heretofore, it was believed, and the prior art so indicates, that only a relatively small hydrogen sulfide partial pressure was required to enhance the hydrocarbon conversion characteristics of a vanadium catalyst. Although it may be expected that those skilled in the art would attempt to adjust the hydrogen sulfide partial pressure in the hope of finding improved conversion characteristics, such a person would not be able to accurately predict a complex correlation between hydrogen sulfide partial pressure and the conversion characteristics of a vanadium catalyst merely by varying the hydrogen sulfide partial pressure unless extensive experimental work had been performed. I not only have found that the conversion characteristics of a vanadium catalyst may be substantially enhanced by increasing the hydrogen sulfide partial pressure but that the degree of conversion does not bear a linear relationship to the partial pressure. Under the circumstances, a vanadium catalyst while in the presence of a narrow range of hydrogen sulfide partial pressure at conversion conditions exhibits an unusually high conversion ability which is completely unexpected.

The criticality of the hydrogen sulfide partial pressure is illustrated in the accompanying drawing. The data utilized in formulating the drawing were obtained in accordance with the specific example hereinafter set forth. Briefly, however, with reference to the drawing, data points 1, 2, 3, 4 and 5 through which curve 6 is drawn were obtained by processing anthracene with a vanadium catalyst at constant conversion conditions, varying only the hydrogen sulfide partial pressure. The criticality attached to the range of hydrogen sulfide partial pressure of from about 10 mole percent to about 25 mole percent is readily ascertained by the character of the curve, in that a hydrogen sulfide partial pressure less than 10 percent or greater than 25 percent exhibits inferior conversion, which is, therefore, not well suited for the production of the desired converted hydrocarbons.

The character of the curve in the drawing is unusual, and totally unexpected in view of the teachings of the prior art respecting the hydrogen sulfide partial pressure as utilized in vanadium catalyzed hydrocarbon conversion.

As hereinbefore set forth, the process of the present invention is particularly directed to the conversion of a hydrocarbon charge stock and more particularly to the conversion of asphaltene-containing hydrocarbonaceous mixtures commonly referred to as black oils. Such charge stocks may be derived from conventional crude oil, tar sand extract, shale oil, coal liquefaction product, etc. However, the hydrocarbon feed to be utilized in the present invention is preferably black oils.

As mentioned previously, the process of the present invention relates to a hydrocarbon conversion process which utilizes a catalyst comprising vanadium. The catalyst may be employed in a fixed bed process, a slurry process or a moving bed process. In a fixed or a moving bed process, the vanadium is preferably associated with a porous inorganic oxide such as silica or alumina. Such catalysts are well known to those skilled in the art and the literature abounds with their methods of preparation. In a slurry process, the vanadium catalyst often is composed of unsupported vanadium or a compound thereof. The unsupported catalyst is colloidally dispersed in the hydrocarbon charge stock and then the mixture of hydrocarbon and vanadium catalyst is reacted in the presence of hydrogen. According to my invention, however, the reaction will occur more favorably in the presence of a critical range of hydrogen sulfide. The slurry process is preferably conducted in an upflow manner.

A particular source of hydrogen sulfide is not required to practice my invention. However, a convenient source of the hydrogen sulfide is a hydrogen sulfide laden gas slipstream removed from the circulating gas in a catalytic hydrocarbon desulfurization unit. Alternatively, essentially pure hydrogen sulfide may be injected into the catalytic reaction zone of this invention.

According to the present invention, hydrocarbon conversion conditions are meant to include a pressure from about 500 psig. to about 5000 psig. and a temperature from about 500F. to about 1000F.

The following example is given to further illustrate the process of the present invention and to indicate the benefits to be afforded through the utilization thereof. It is understood that the example is given for the sole purpose of illustrating the means by which curve 6 in the accompanying drawing is obtained, and that the example is not intended to limit the generally broad scope and spirit of the appended claims.

EXAlVlPLE The data presented in this example is pertinent to the accompanying drawing, and the latter should be referred to in conjunction with the following discussion. The hydrocarbon charge stock utilized in the test procedure for evaluating the effect of hydrogen sulfide partial pressure was a practical grade anthracene. Finely divided vanadium tetrasulfide was selected to be the catalyst precursor for this example.

A 0.72 gram sample of vanadium tetrasulfide (V8 was placed in an 850 cc. rotating autoclave with 25 g. of anthracene. After the air had been purged from the autoclave vessel, the required amount of hydrogen sulfide was added and then the vessel was pressure to atmospheres (1470 psig.) with hydrogen. The temperature of the vessel was increased to 350C. (662F.) and held at this temperature for 2 hours. Then the vessel was cooled at room temperature and depressured. The recovered hydrocarbon product was analyzed by chromatography to determine the percentage of hydrocracked product as a percentage of the recovered hydrocarbon liquid.

In the first run, no hydrogen sulfide was added and the hydrocracked product was only 11.3 volume percent. During the next four runs, sufficient hydrogen sulfide was added to create a hydrogen sulfide partial pressure of 7.01, 9.98, 21.1 and 30.8 mole percent, respectively and the hydrocracked product was 24.6, 40.9, 45.7 and 5.0 volume percent, respectively.

A summary of the results of the hereinabove described runs are presented below in Table I.

Liquid, 7:

As described briefly hereinabove, the drawing was obtained by plotting the data points, 1, 2, 3, 4 and 5 which correspond directly with Runs 1 through 5. Curve 6 was then drawn along the plotted data.

From the drawing, which is a pictorial representation of the effect of hydrogen sulfide partial pressure upon the hydrocracking capabilities of a vanadium catalyst, it can easily be seen that the most favorable hydrocracking yields are obtained with a hydrogen sulfide partial pressure from about 10 to about 25 mole percent.

The foregoing specification and example clearly illus trate the improvements encompassed by the present invention and the benefits to be afforded a process for the maximization of conversion ability of a vanadium catalyst.

I claim as my invention:

1. A process for the conversion of a hydrocarbon charge stock which comprises admixing said charge stock with a catalyst comprising vanadium and reacting the resulting mixture with hydrogen and added hydrogen sulfide at hydrocarbon conversion conditions, characterized in that the partial pressure of said hydrogen sulfide is from about 10 mole percent to about 25 mole percent.

2. The process of claim 1 further characterized in that said catalyst comprising vanadium is an unsuppported vanadium sulfide catalyst.

3. The process of claim 1 further characterized in that said hydrocarbon charge stock is asphaltene containing black oil.

4. The process of claim 1 further characterized in that said hydrocarbon conversion conditions comprise a pressure from about 500 psig. to about 5000 psig., and a temperature from about 500F. to about 1,000F. 

1. A PROCESS FOR THE CONVERSATION OF A HYDROCARBON CHARGE STOCK WHICH COMPRISES ADMIXING SAID CHANGE STOCK WITH A CATALYST COMPRISING VANADIUM AND REACTING THE RESULTING MIXTURE WITH HYDROGEN AND ADDED HYDROGEN SULFIDE AT HYDROCARBON CONVERSATION CONDITIONS, CHARACTERIZED IN THAT THE PARTIAL PRESSURE OF SAID HYDROGEN SULFIDE IS FROM ABOUT 10 MOLE PERCENT TO ABOUT 25 MOLE PERCENT.
 2. The process of claim 1 further characterized in that said catalyst comprising vanadium is an unsupported vanadium sulfide catalyst.
 3. The process of claim 1 further Characterized in that said hydrocarbon charge stock is asphaltene containing black oil.
 4. The process of claim 1 further characterized in that said hydrocarbon conversion conditions comprise a pressure from about 500 psig. to about 5000 psig., and a temperature from about 500*F. to about 1,000*F. 